Rounding decimals

​​In a nutshell

Just like with whole numbers, decimals can be rounded up or down using very similar rules. 

Rounding to the nearest whole number

​​Definition

​Rounding to the nearest whole number means to round a decimal up or down to the nearest whole number.​

Rounding decimals with one decimal place

PROCEDURE

1. ​Look at the digit in the tenths column.
   
2. If the digit is $$0,1,2,3$$ or $$4$$, round down to the nearest whole number.
3. If the digit is $$5,6,7,8$$ or $$9$$, round up to the nearest whole number.​

Example 1

Round $$1.9$$ to the nearest whole number.

Look at the tenths digit.

The digit in the tenths column is $$9$$.

Round up to the next whole number.

​$$1.9\rightarrow\underline2$$​​

Rounding decimals with two or more decimal places

If a number has two or more decimal places, the process is exactly the same. Only the number in the tenths column is of any importance.

Example 2

Round $$3.28$$ to the nearest whole number.

Look at the tenths digit.

​The digit in the tenths column is $$2$$​.

Round down to the closest whole number.

​$$3.28\rightarrow\underline{3}$$​​

Rounding to one decimal place

​​Definition

​Rounding to one decimal place (or the nearest tenth) means to round a decimal up or down to the closest one decimal place.

Procedure

1. ​Look at the digit in the hundredths column.
   
2. If the digit is $$0,1,2,3$$ or $$4$$, round down to the nearest one decimal place.
3. If the digit is $$5,6,7,8$$ or $$9$$, round up to the nearest one decimal place.

​​​

Example 3

Round $$8.76$$ to one decimal place.

Look at the hundredths digit.

The digit in the hundredths column is $$6$$.

Round up to the closest tenth.

​$$8.76\rightarrow\underline{8.8}$$

​

Note: A number rounded to one decimal place (or the nearest tenth) should have no digits to the right of the tenths digit.